Catalyst system for fabric finishing process



United States Patent 3,212,928 CATALYST SYSTEM FOR FABRIC FINISHING PROCESS Henry R. Hushebeck, Wilmington, Del., assignor to Joseph Bancroft & Sons Company, Wilmington, Del., a corporation of Delaware No Drawing. Continuation of application Ser. No. 762,934, Sept. 24, 1958. This application June 21, 1962, Ser. No. 204,070

4 Claims.

This application is a continuation of my co-pending application Serial No. 762,934 filed September 24, 1958, now forfeited.

This invention relates to the treatment of cellulosic fabrics and other long chain hydroxylated polymeric materials with ketone-aldehyde precondensates and to an acid catalyst system which is especially useful in connection therewith.

Heretofore, ketone-aldehyde resins have been employed as finishing agents for various textiles. In such processes the practice heretofore has involved impregnating the fabtie with a heat hardenable ketone-aldehyde precondensate and thereafter curing or hardening the resin in the presence of alkaline curing catalysts. The fabric finished in this way is characterized by many desirable attributes such as dimensional stability, crease recovery and non-chlorine retentiveness. The process is also useful to impart durable or washfast mechanical finish effects to fabrics. Despite the very obvious and highly desirable fabric finishing characteristics of these resins the textile industry has for the most part neglected the ketone-aldehyde resins for the reason that the resin finish is readily discolored by light and by laundering thus rendering these resins unsuitable for fabric finishing purposes-particularly where white goods are involved.

I have discovered that one of the causes of the poor light fastness and launderability of the ketone-aldehyde resin finished fabrics is due to the fact that the alkaline cured resin retained in and on the fabric and its fibers can be readily activated by sunlight and also by alkali; this activation causes structural rearrangements of the resin which brings on the objectionable discoloration.

I have further found that if along chain hydroxylated polymer such as cellulose is impregnated with a ketonealdehyde precondensate it is possible to impart durable finish effects by heating the fabric under certain specially provided acid conditions and that the finishes obtained in this way are not subject to discoloration as in the case of the alkaline cured resin. At the same time the desirable properties of the finish are not impaired.

The fabric finish imparted according to my invention differs from conventional resin finishes in that the finished fabric does not retain appreciable quantities of condensed resinous materials and undergoes little change in weight during processing even when the fabric is initially impregnated with very high concentrations of ketone-aldehyde precondensates.

For the purpose of finishing fabrics with ketone aldehyde precondensates and where the heat treatment is effected on the acid side, the mere presence of any acid material will not suffice to produce a satisfactory finish.

When either acids or acid salts are used alone as the catalyst for fabrics impregnated with ketone-aldehyde precondensates, in order to obtain, to a maximum extent, the benefits of the desirable finish characteristicssuch as for example, improved crease recoveryit is necessary to operate under conditions in which either very high catalyst concentrations are used or the temperature of the heat treatment must be rather severe. In either case the conditions needed to maximize the influence and effect of desirable properties imparted by the treatment are such that the fabric will be degraded and weakened to a degree ice which renders the fabric commercially unsatisfactory. In other words, desirable properties such as crease recovery can be enhanced only at the expense of a concurrent strength loss. High catalyst concentrations of either an acid or an acid salt alone also have been found to undesirably discolor the finish during the heat treatment to fix the finish effect.

It is one of the objects of this invention to provide an acid catalyst system for fixing finish effects imparted to fabrics impregnated with ketone-aldehyde precondensates without discoloring or objectionably tendering the fabric and at the same time enhancing desirable finish characteristics such as crease recovery.

It is another object of this invention to provide a new method for finishing textile fabrics with ketone-aldehyde precondensates.

Other objects and advantages of the invention will appear in the following description.

In accordance with my invention, the various objects and advantages are secured by the use of a special acid catalyst system for the treatment of cellulose and other long chain hydroxylated polymers wtih ketone-aldehyde precondensates; and, as will be brought out in greater detail hereinafter, the acid catalyst system involves the use of a special combination of two acidic components, (a) an acid, and (b) an acid salt of the Lewis acid type.

The term ketone-aldehyde precondensates as used herein refers to precondensates prepared by condensing or reacting a ketone and an aldehyde under alkaline conditions. These precondensates range from the relatively simple precondensates prepared by reacting acetones and formaldehyde to the structurally more complex precondensates prepared by reacting higher ketones with higher aldehydes. The ketone aldehyde precondensates which are most frequently used as textile finishing agents are those prepared from ketones and aldehydes which, at the lower stages of condensation, form precondensates that are water soluble or that can be readily dispersed in the medium used to apply the resin to the fabric. The acetone formaldehyde precondensates, hereinafter referred to as methylol acetones, have been found to be especially useful for these purposes, as the raw materials are inexpensive and water soluble precondensates can be prepared therefrom by reacting 1 mol of acetone with from about 1 to 8 mols of formaldehyde in the presence of alkaline catalysts. However, even the more complex ketone-aldehydes are useful as fabric finishing agents (see British Patent 538,452) and this invention can be used in conjunction therewith.

Turning now to a consideration of the special catalyst system of this invention. It is a two component systemone component being an acid and the other component being an acid salt of the Lewis acid type.

Suitable acids for the purposes of this invention include organic and inorganic acids and acid anhydn'des such as maleic, tartaric, phosphoric, citric, itaconic, succinic, and the like. .I prefer, however, to employ polybasic acids since catalyst combinations prepared therefrom in accordance with the invention will develop the desired degree of acidity for efiicient finishing and will not, under the finishing conditions employed for treating the impregnated fabrics, develop acidity to a degree which will seriously degrade the cellulose or other hydroxylated polymeric fabric base. Acids which are weakly acidic, such as formic acid, are not well suited for purposes of this invention as they do not permit efficient finishing within time and temperature relationships involved in commercially available equipment.

The preferred acid salts for use in the catalyst system of this invention are the metal salts of either organic or inorganic acids of the Lewis acid type (i.e. an electron acceptor) and especially the polyvalent metal salts of such acids and the acid salts of monovalent metals with polybasic acids. However, where white goods are to be finished, I prefer to employ those salts of the Lewis acid .type which form substantially colorless aqueous solutions.

Examples of such acid salts which have been found to be especially useful are aluminum chloride, strontium chloride, tin chloride, aluminum acetate, magnesium chloride, zirconium oxychloride, zinc nitrate, and

the like. Where one or more of these acid salts are used in combination with the preferred acids, the catalyst system thereby formed will permit eflicient finishing of cellulosic fabrics impregnated with ketone aldehyde precondensate without objectionably degrading the fabric base material and the finished fabric is not subject to discoloration during finishing or upon laundering, and other desired finish characteristics will be maximized to an extent not possible where either the acid or acid salt is used alone.

I prefer to apply the precondensate and the catalyst system to the fabric from the same treating bath, as only employ impregnating baths in which the solids content of the ketone-aldehyde precondensate constitute from about 2.5 to 50% of the total weight of the bath. The catalyst system can constitute from about 0.3 to 20% of the total weight of the bath. The bath can also contain buffers and other conventional finishing agents such as softeners, wetting agents, tinting agents and the like.

The relative ratio of the acid to the acid salt employed can vary over a wide range provided that the combination is one which will develop under the heating conditions involved in the finishing operation and in the presence of the impregnated precondensate, an acidity which is sufiicient to enable the finish effect to be fixed efficiently and without objectionably degrading the fabric. For example, weight of the acid component in the impregnating bath can range from as little as 0.1% Where relatiely strong acids are used to as much as where relatively milder acids are employed, and the acid salt component can likewise range from 0.2 to 10% of the total bath weight depending on the relative acidity of the salt employed. However, fabrics which exhibit a pH of about 2.0 to 4.5 after heating appear to be the most satisfactory from the standpoint of minimization of tendering and discoloration and enhancement of desirable fabric finish properties. I prefer to employ treating bath which will give the fabric, after heating, a pH of about 2.0 to 4.5. Since the pH of the fabric after the heat treatment is usually the same or slightly higher than the pH of the impregnated bath, I therefore prefer acid and acid salt combinations which form a bath having this general order of pH range. It is however, possible, where stronger acids and acid salts are employed in combination, to secure satisfactory results with baths having a pH as low as 1.0 either employing such materials in relatively low concentration by increasing the concentration of the precondensate impregnated in the fabric, or by heating the impregnated fabric at lower temperatures. For example, satisfactory results can be obtained by using a 0.2% aluminum chloride and 0.1% hydrochloric acid with a fabric impregnated with 46% ketone aldehyde precondensate by heating the fabric for 3 minutes at 275 F. Conversely, where the weaker acids and acid salts are employed in combination, satisfactory results can also be obtained where the pH of the bath is as high as about 5.5 by either employing such materials in relatively high concentrations by decreasing the concentration of the precondensate impregnated in the fabric or by raising the temperature. For example, satisfactory results can be obtained by using 10% magnesium acetate and 10% succinic acid to finish a fabric impregnated With 46% ketonealdehyde precondensate by heating the fabric for 3 minutes at 275 F.

Satisfactory results can also be obtained with combinations of strongly acidic acids and weakly acidic salts of the Lewis acid type, and with combinations of weakly acidic acids with strongly acidic salts of the Lewis acid type. In such cases, the stronger material is employed in relatively low concentration and the weaker material is in relatively high concentrations. For example, combinations such as 0.1% phosphoric acid and 10% magnesium nitrate and combinations such as 10% succinic acid and 0.2% aluminum chloride have both been found to give satisfactory results in finishing fabrics impregnated with 46% ketone-aldehyde precondensates by heating the fabric for 3 minutes at 275 F.

In the foregoing comparisons, all percentages were based on the fabric weight.

Further, with respect to the concentration of catalyst employed during the finishing treatment, it should be observed that the presence of the ketone-aldehyde precondensate on the fabric exhibits a buffering action on the catalyst system, therefore, more catalyst will be needed for finishing fabrics having heavy precondensates concentration than where the precondensate is present in low concentration. Further, in connection with the use of the ketone-aldehyde as finishing agents, it is important to observe that acidic catalysts alone are not effective agents for condensing the ketone-aldehyde resin precondensates to water insoluble polymers. If an aqueous solution containing only the ketone-aldehyde precondensate and the acid catalyst, even when prepared in accordance with this invention, is placed on a glass slide and evaporated to dryness and thereafter baked at elevated temperatures of the order of 275 F. for as long as 1 hour, the film of material left on the glass slide will not be completely insolubilized; nevertheless, if ,cellulose or some other similar long chain hyd-roxylated polymeric material is present cojointly with the precondensate and catalyst at the time of heating, reactions occur which cause the properties of the long chain polymer to be modified and the finish effects imparted in this way are rendered durable.

In connection with the heat treatment, it should be observed that the finishing of fabrics impregnated with the keto-ne aldehyde precondensate can be effected under much less severe conditions than in the case of urea formaldehyde and melamine type textile finishing agents. With the ketone-aldehydes, finish effects can be set or fixed by heating the fabric to temperatures as low as F. for about 30 minutes. The operation to fix the finish can be accelerated by heating the fabric to temperatures of the order of 400 F. for a few seconds. In addition it is also possible to effect heating by means of infrared radiation, in which case the impregnated fabric is passed between infrared plates spaced about 12" apart and heated to a temperature of about 850 F.; in which case the time of passage of the fabric can then be cut down to as low as 5 seconds.

The catalyst system and the process of this invention can be effectively utilized to impart and enhance various different fabric finish effects such as dimensional stability, cnease recovery, and provide a finish which is non-chlorine retentive. The manipulative aspects of such finishing operations are all well known and understood by those skilled in the art. In addition, it is also possible to use the catalyst system and the process of this invention to impart durable or washfast mechanical finish effects to fabrics of the type heretofore produced using thermosetting resins such as urea formaldehyde, melamine formaldehyde and the like. With respect to both types of finishes (i.e. mechanical and non-mechanical) it should be observed that it is customary where resinous impregnants are employed to. dry the. fabric before the final curing or hardening. In the production of mechanicalfinish effects by the use of the ketone-aldehyde precondensates and the special catalyst system of this invention, the moisture content of the fabric at the time of imparting the mechanical finish should range generally from about 8 to 20% total moisture.

It is also desirable to thoroughly wash the fabric after the final heat treatment to remove unfixed residues. Various of the improvements contemplated by the different aspects of the invention will be illustrated in some- What greater detail in the examples given hereinafter. All formulas are given in terms of percent by weight of the pad bath and are based on a solution'pick-up of 100% of the fabric weight. The ketone-aldehyde precondensate is a methylol acetone solution containing approximately 30% solids.

Example I A cotton textile fabric is padded through the following mixture and dried and then heated to a temperature of 160 F. for a period of 30 minutes. It was subsequently washed and dried, resulting in a soft supple fabric possessing improved crease recovery properties and commercially satisfactory strength.

Cotton fabric is padded through the above mixture, dried and then heated by passing the dried fabric between infrared heating plates at a. temperature of 850 F. for 5 seconds and washed and dried, resulting in a fabric having good crease recovery and commercially satisfactory strength.

Example III Percent Ketone aldehyde precondensate 32.0 Citric acid 5.0 Chromium chloride 0.2 Water 62.8

When padded on cotton, dried and then heated at 275 F. for 3 minutes, a supple fabric of improved crease recovery, and commercially satisfactory strength is obtained.

Example IV Percent Ketone aldehyde precondensate 36.00 Phosphoric acid (75%) 0.38 Zinc nitnate 1.60 Water 62.02

A strong soft supple fabric with improved crease resistance was obtained when the above mixture was padded on cotton fabric, dried and then heated for 3 minutes at 260 F. The fabric was washed and dried for the final result.

6 Example V Percent Ketone aldehyde precondensate 85.0 Citric acid 1.7 Magnesium nitrate 10.0 Water 3.3

The procedure for Example V is followed except that the fiabric is heated to 240 F. for 3 minutes with comparable results.

Example VI Percent Ketone aldehyde precondensate 85.0 Maleic acid 10.0 Zinc nitrate 1.6 Water 3.4

The procedure for Example V is followed except that the fabric is heated for a period of 3 minutes at 240 F. with comparable results.

Example VII Percent Ketone aldehyde precondensate 46.0 Citric acid 2.2 Chromium acetate 1.2 Water 50.6

A cotton fabric was padded through the above treating solution, dried and then heated to 235 .F. for 3 minutes after washing, and drying, a soft supple fabric with enhanced crease recovery and satisfactory strength was obtained.

Example VIII Percent Ketone aldehyde precondensate 7.5 Citric acid 0.33 Strontium nitrate 0.50 Magnesium nitrate 0.70 Water 90.97

The procedure of Example VIII was followed with the exception that the heat treatment was for 3 minutes at 320 F. Comparable results were obtained.

By following the procedure of Example VIII and heating to 260 F. for 3 minutes, a fabric of improved crease recovery with a soft supple hand and very good strength was obtained.

I claim:

1. A catalyst system consisting essentially of a mixture of two compoents, one of said components being a polybasic acid and the other of said components being a polyvalent metal salt of the Lewis acid type, said catalyst system being characterized in that upon heating it will provide an environment that is capable of curing fabrics which have been impregnated with ketone-aldehyde precondensates.

2. A catalyst system according "to claim 1 wherein the metal salt is substantially colorless in aqueous solution.

3. The method of finishing fabrics which comprises impregnating the fabric with a ketone-aldehyde precondensate and heating the impregnated fabric in the presence of the catalyst system of claim 1. v

4. The method of finishing cellulosic fabrics which comprises impregnating the fabric with an aqueous solution containing a water soluble methylol acetone together with a mixture consisting essentially of a polybasic acid and a polyvalent metal salt of the Lewis acid type which will provide an impregnating solution having a pH of from 1.0 to 5.5, and thereafter heating the fabric.

References Cited by the Examiner UNITED STATES PATENTS Semon 252428 Bener 117-139.4 XR Miller 26064 Miller et a1. 1l7--145 XR Wright et a1. 117l61 XR Hessel et a1. 260-6 WlLLIAM D. MARTIN, Primary Examiner. 

1. A CATALYST SYSTEM CONSISTING ESSENTIALLY OF A MIXTURE OF TWO COMPONENTS, ONE OF SAID COMPONENTS BEING A POLYBASIC ACID AND THE OTHER OF SAID COMPONENTS BEING A POLYVALENT METAL SALT OF THE LEWIS ACID TYPE, SAID CATALYST SYSTEM BEING CHARACTERIZED IN THAT UPON HEATING IT WILL PROVIDE AN ENVIRONMENT THAT IS CAPABLE OF CURING FABRICS WHICH HAVE BEEN IMPREGNATED WITH KETONE-ALDEHYDE PRECONDENSATES.
 3. THE METHOD OF FINISHING FABRICS WHICH COMPRISES IMPREGNATING THE FABRIC WITH A KETONE-ALDEHYDE PRECONDENSATE AND HEATING THE IMPREGNATED FABRIC IN THE PRESENCE OF THE CATALYST SYSTEM OF CLAIM
 1. 